What would you do to fix this?

[Willsa]

Hi guys!
I had so many jobs lined up to complete outside this summer... The weather

With an unfortunate start/stop/start approach I have been lowering the ground levels around my Victorian house.
The soil was breaching the slate damp course and ending on the air bricks. Add to that the virtual lack of gutters/drainage (now sorted) and the old, soft clay bricks have been melting away.

In the photo one of the worst damages is visible but there's quite a few areas like it. The brick has crumbled, some of the slate missing.

* do I find reclaimed brick to replace?
* which particular mortar&pointing would you use? The finished ground level will be a brick and a half below the slate DPC.
*what mortar would you use below ground? Some big holes and missing whole bricks there!

Thank you!

 

[Cubist]

Hi Willsa,
Yeah, it's been a real wash out this year so far and theres little sign of improvement. I would go for reclaimed bricks if at all possible, theres a better chance of getting the same dimensions and it can be a real pain when the replacements fail to match the L/B/D of the originals. Better chance also of finding a colour match too, albeit that's not so important for those to be laid near/below ground. Lime mortar every time but have no particular preference re the strength. The caveat, as always, is to get rid of any Portland cement before laying the replacement bricks and re-pointing.

Cheers, and hoping the weather begins to smile on all of us soon.
Cubist

 

[MatthewC]

If it's going to stay wet down that far, I'd use NHL 3.5 or even 5

 

[Willsa]

I'm in a right pickle here....
I've dug down to foundations to allow my "cake layers" of drainage improving materials. Was fully expecting some repointing but there's quite a lot of damage to the brickwork that was previously soaking under concrete in wet clay for decades

Apart from old cut-off clay pipes literally channelling water into the floor void and missing whole bricks, my current concern is regarding the pointing - in some areas there's none left, it's just mud. Can remove it all the way with a stick.

Can I use a cement-based mortar underground? The earth is so damp here, that even my sustainable drainage systems won't make it dry. Just hopefully not water-logged.

Do I rake out the dirt one brick run at a time, repoint and then do the next one down? Doesn't seem safe to remove all the compressed earth from the joints at once... Slowly does it?

I definitely have a bloomin' good view now to understand why the dry rot has chosen to eat the ground floor of this house!

 

[a twig]

The mud is probably old lime and earth mortar, you don’t need to take out all the old earth mortar, just enough to repoint, obviously in places where it is completely missing then there is no need to rake out at all, just a quick brush and then good to go.

In the upside at least you won’t need to worry about the mortar drying out too quickly and faffing around with water spray bottles!

Whack the NHL 3.5 in and you’ll be good to go I reckon. Replace missing bricks, remove the old pipes and that will make a huge difference. Hydraulic lime mortars are fine underwater so no issues in damp/wet soil.

 

[noj]

Just to add, maybe don't do it a run at a time, do it in sections, bottom up. Think pillars of support!

 

[Willsa]

Cause of Twig I stayed up waaaay too late reading on earth mortars
Never knew about them - but it clearly looks like the case here!
Now the lower walls are all exposed I can tell exactly where the earth mortars are by the look of the walls - the clay subsoil mortar dries out very slowly, so the walls in those areas are still the colour of a wet brick.
The base of the bay is lime and that has gone all dry, dusty white. Dunno why the difference in pointing materials and what the thinking was behind it (if any!)

I'll go to lime merchants today for some NHL 3.5 as I'm not going like for like and sticking some clay mud back in there. Christ on a bike, what a house!

 

[a twig]

The bay may well have been added later, or rebuilt at some point. Best of luck with it all